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Laser surface alloying of sintered stainless steels with SiC powder

Brytan Z., Dobrzański L. A., Pakieła W.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 47, nr 1

42--56

EN

Purpose: The goal of this study is to investigate effects of laser surface alloying with SiC powder on microstructural changes and properties of vacuum sintered austenitic X2CrNiMo17-12-2, ferritic X6Cr13 and duplex X2CrNiMo22-8-2 stainless steels. Design/methodology/approach: Surface modification of sintered stainless steels was carried out by laser surface alloying with SiC powder using high power diode laser (HPDL). The influence of laser alloying conditions, the laser beam power (between 0.7 and 2.1 kW) at constant scanning rate on the width of alloyed surface layer and penetration depth were studied. The resulting microstructure in laser alloyed surface layer was examined using light and scanning electron microscopy. Phase composition was determined by the X-ray diffraction method. The microhardness results of modified surface layer were also studied. Findings: The alloyed surface layer has a fine dendritic microstructure with iron-chromium carbides precipitations. The surface layer was enriched in silicon and carbon that produced microstructural changes and resulting microhardness increase. Beside studied stainless steels the duplex one revealed highest hardening effect by laser alloying with SiC powder, where related microhardness was about 500-600 HV Practical implications: Laser surface alloying with SiC powder can be an efficient method of surface layer hardening of sintered stainless steels and produce significant improvement of surface layer properties in terms of hardness and wear resistance. Originality/value: Application of high power diode laser can guarantee uniform heating of treated surface, thus uniform thermal cycle across processed area and uniform penetration depth of alloyed surface layer.

2

Laser treatment of the surface layer of 32CrMoV12-28 and X40CrMoV5-1 steels

Dobrzański L. A., Labisz K., Jonda E.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 29, nr 1

63-70

EN

Purpose: This work presents the investigation results of laser remelting and alloying especially the laser parameters and its influence on the structure and properties of the surface of the 32CrMoV12-28 and X40CrMoV5-1 hot work steels, using the high power diode laser (HPDL). In this paper there are presented the investigation results of mechanical properties and microstructure with ceramic particle powders VC vanadium carbide and WC tungsten carbide. The purpose of this work was also to determine the laser treatment conditions for surface layer treatment of the investigated steels. Design/methodology/approach: The purpose of this work was the determination of technological conditions for alloying and remelting of the surface layer particularly the laser power. There is studying the influence of treatment on the remelting depth of the surface layer to achieve high layer hardness for protection of the steel and also make the surface more resistant for work. Findings: As a result structure changes in form of fragmentation were determined. For alloying the tungsten carbide and vanadium carbide powders were used. Two phases of carbides, VC and WC, were observed. Research limitations/implications: The remelted layers which were formed on the surface of the investigated hot work steel were examined metallographically and analyzed using a hardness and micro hardness testing, X-ray diffraction, EDS microanalysis, electron scanning microscope. Practical implications: This work helps to use the new developed laser treatment technique for alloying and remelting of hot work tool steel tools for hot working conditions. Originality/value: The originality of this work is based on applying of High Power Diode Laser for improvement of steel mechanical properties as well the thermal fatigue and wear resistance.

3

Laser surface treatment of magnesium alloy with WC and TiC powders using HPDL

Dobrzański L., Domagała J., Tański T., Klimpel A., Janicki D.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 28, nr 2

179-186

EN

Purpose: The aim of this work was to improve the surface layer cast magnesium alloy EN-MCMgAl6Zn1 by laser surface treatment. The purpose of this work was also to determine the laser treatment parameter. Design/methodology/approach: The laser treatment of an EN-MCMgAl6Zn1 magnesium alloy with alloying WC and also TiC powders was carried out using a high power diode laser (HPDL). The resulting microstructure in the modified surface layer was examinated using scanning electron microscopy. Phase composition was determined by the X-ray diffraction method using the XPert device. The measurements of microhardness of the modified surface layer was also studied. Findings: The alloyed region has a fine microstructure with hard carbide particles. Microhardness of laser surface alloyed layer with both TiC and WC particles was significantly improved as compared to alloy without laser treatment. Research limitations/implications: In this research two powders (WC and TiC) were used with the particle size over 5 µm This investigation presents different speed rates feed by one process laser power. Practical implications: The results obtained in this investigation were promising to compared other conventional processes. High Power Diode Laser can be used as an economical substitute of Nd:YAG and CO2 to improve the surface magnesium alloy by feeding the carbide particles. Originality/value: The originality of this work is applying of High Power Diode Laser for alloying of magnesium alloy using hard particles like tungsten carbide and titanium carbide.

4

Mechanical and tribological properties of the surface layer of the hot work tool steel obtained by laser alloying

Dobrzański L. A., Jonda E., Križ A., Lukaszkowicz K.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 7

389-396

EN

Purpose: The paper presents results on the mechanical and tribological properties examinations of the X40CRMoV5-1 hot work alloy tool steel alloyed with carbide powders using the high power diode laser (HPDL). Design/methodology/approach: Metallographic examinations of the material structures after laser alloying of their surface layer were made on light microscope. The tribological wear relationships using pin-on-disc test were specified for surface layers subject to laser treatment, determining the friction coefficient, and mass loss of the investigated surfaces. Hardness tests were made with Rockwell method in C scale on specimens subjected to the standard heat treatment and alloyed using the high power diode laser at various parameters. X-ray diffraction (XRD) technique was used to investigate crystalline structure and phases in the layers. Findings: Metallographic examinations carried out on the light microscope confirm that the structure of the material solidifying after laser remelting is diversified, which is dependant on the solidification rate of the investigated steels. The investigations carried out made it possible to state that due to the heat treatment and remelting of the X40CrMoV5-1tool steel with the WC, TaC or TiC powders it is possible to obtain the high quality surface layer with no cracks and defects and with hardness significantly higher than the substrate metal. Research limitations/implications: In order to evaluate with more detail the possibility of applying these surface layers in tools, further investigations should be concentrated on the determination of the thermal fatigue resistance of the layers. Practical implications: The alloyed layers which were formed on the surface of the hot work steel have shown significant improvement. Good properties of the laser treatment make these layers suitable for various technical and industrial applications. Originality/value: A modification of tool steels surface using a laser beam radiation, as well as coating them with special pastes containing carbides particles such as tungsten, tantalum and titanium allows the essential improvement of the surface layer properties-their quality and abrasion resistance, decreasing at the same time the surface quality.